GGG Rangemaster NPN Question - D1?

[Stratman]

Hi guys,

I thought I'd have a go at building a NPN Rangemaster on a GGG board. I just got the board, and I have been checking out the parts I have and I noticed that the project allows for a protection diode as "optional", but the board doesn't have a "D1" printed on it (mistake or is D1 offboard?). This is a multipurpose board, and I'm a bit confused. From looking at the board, I am guessing for the NPN version I can put the diode in R5 the "Jumper"? (Neewbie, please humour me). "B" is +9v. I suspect my assumption about R5 probably isn't right, as I suspect if the voltage was reversed, the led diode would see the reversed current anyway and blow?

I guess the sure fire way is to connect a protection diode in series straight to the dc jack, but if it were on the board it would be nicer.

Here's the doco:

Layout
and scheme.

Any help greatly appreciated

[PRR]

> put the diode in R5 the "Jumper"?

I think that is power and signal Ground.

[Stratman]

Hi PRR,

Thank you! It was a very basic neewb question I'm sure - and you even included a diagram to illustrate - thanks for the effort You've made my day.

Strangely enough I was going to try, a diode to "B", as it did seem more logical on reflection. On the GGG instructions it's a bit vague about the diode (scheme is obvious) and R10 is also mysteriously not named as a jumper as well. The rest looks easy enough to follow.

Cheers,
Stratman